Check out and check in

Before you modify user role assignments, security profiles, or security profile assignments, you must check out the user security structure. You cannot check out the user security structure unless all dimensions are checked in. After the user security structure is checked out, no one can check out dimensions until the user security structure is checked back in. Only one person at a time can check out the user security structure. If necessary, you can undo your security structure check out at any time before completing a check-in.